SynthesisMolecular psychiatry2021
The kynurenine pathway in major depressive disorder, bipolar disorder, and schizophrenia: a meta-analysis of 101 studies.
Synthesis in Molecular psychiatry, 2021. The graph could read no effect estimate from its abstract, so it casts no vote on the map. It is linked to trial NCT07060690 (A Women-Centered Approach), which is not on this map. Cited by 168 papers, 7 of them syntheses that pooled it.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
A Women-Centered Approach: Evaluating a Human-Supported Online Intervention for Depression. Study on Its Efficacy and the Metabolic Signature of Personalised Treatment Response
Who cites it
168 citing papers in PubMed, 7 syntheses or guidelines pooled it, 297 citations in OpenAlex.
- Multimodal microglial and kynurenine pathway alterations across the affective-psychosis spectrum: a systematic review of patterns, heterogeneity, and dimensional implications.Molecular psychiatry · 2026Pooled it
- A working model linking the psychopathology and pathophysiology of major depressive disorder - an umbrella review of neuroimaging studies and a conceptual framework.Molecular psychiatry · 2025Pooled it
- Nutraceuticals and phytoceuticals in the treatment of schizophrenia: a systematic review and network meta-analysis "Nutra NMA SCZ".Molecular psychiatry · 2025Pooled it
- The tryptophan catabolite or kynurenine pathway in schizophrenia: meta-analysis reveals dissociations between central, serum, and plasma compartments.Molecular psychiatry · 2022Pooled it
- Non-Invasive Brain Stimulation Effects on Biomarkers of Tryptophan Metabolism: A Scoping Review and Meta-Analysis.International journal of molecular sciences · 2022Pooled it
- Dynamic changes in metabolites of the kynurenine pathway in Alzheimer's disease, Parkinson's disease, and Huntington's disease: A systematic Review and meta-analysis.Frontiers in immunology · 2022Pooled it
- BrainFrontiers in immunology · 2021Pooled it
- Tryptophan-enriched diet or 5-hydroxytryptophan supplementation given in a randomized controlled trial impacts social cognition on a neural and behavioral level.Scientific reports · 2021Trial
- Metabolic Effects of Healing Touch During Cervical Cancer Treatment: An Exploratory Analysis.Integrative cancer therapiesTrial
- The role of the kynurenine pathway in the pathogenesis of pain and affective disorders after traumatic brain injury.Brain, behavior, & immunity - health · 2026Review
- The Tryptophan-Kynurenine Pathway as a Key Mediator of the Gut-Brain Axis in Depression and Alzheimer's Disease.International journal of molecular sciences · 2026Review
- Advancing Prostate Cancer Survivorship through Transatlantic Consortium Science: The iCCaRE Initiative.Cancer research communications · 2026Article
- Dietary Tryptophan Allocation in Depression: Serotonin-Kynurenine Balance, Microbial Indole Pathways, and Inflammatory Phenotypes.Nutrients · 2026Review
- A Women-Centered Internet-Based Cognitive Behavioral Therapy for Depressive Symptoms (the 3D Program): Protocol for a Randomized Controlled Trial.JMIR research protocols · 2026Article
- Molecular and Cellular Mechanisms Linking Mood Disorders, HPA Axis Dysregulation, and Neurocognitive Inflammation to Perioperative Neurocognitive Disorders.Biomolecules · 2026Review
- Association Between Kynurenine Pathway and Cerebellar Microstructure in Bipolar Disorder With Childhood Trauma.Alpha psychiatry · 2026Article
- The Effects of Transcranial Magnetic Stimulation on Tryptophan Metabolism and Depressive-Like Behavior in Mice.Brain and behavior · 2026Article
- The potential role of kynurenine pathway and inflammation in pediatric obsessive-compulsive disorder with and without major depressive disorder comorbidity.Journal of neural transmission (Vienna, Austria : 1996) · 2026Article
- Exercise mimetics as unexplored therapeutics for treating depression.Molecular psychiatry · 2026Article
- Vitamin D as a Lifespan Neuroimmune Signal in Psychiatry: From Developmental Risk to Precision Nutrition.Nutrients · 2026Review
108 more citing papers are in PubMed but not listed here.
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
21 authors at 9 institutions in 8 countries.
Funding
Abstract
The importance of tryptophan as a precursor for neuroactive compounds has long been acknowledged. The metabolism of tryptophan along the kynurenine pathway and its involvement in mental disorders is an emerging area in psychiatry. We performed a meta-analysis to examine the differences in kynurenine metabolites in major depressive disorder (MDD), bipolar disorder (BD), and schizophrenia (SZ). Electronic databases were searched for studies that assessed metabolites involved in the kynurenine pathway (tryptophan, kynurenine, kynurenic acid, quinolinic acid, 3-hydroxykynurenine, and their associate ratios) in people with MDD, SZ, or BD, compared to controls. We computed the difference in metabolite concentrations between people with MDD, BD, or SZ, and controls, presented as Hedges' g with 95% confidence intervals. A total of 101 studies with 10,912 participants were included. Tryptophan and kynurenine are decreased across MDD, BD, and SZ; kynurenic acid and the kynurenic acid to quinolinic acid ratio are decreased in mood disorders (i.e., MDD and BD), whereas kynurenic acid is not altered in SZ; kynurenic acid to 3-hydroxykynurenine ratio is decreased in MDD but not SZ. Kynurenic acid to kynurenine ratio is decreased in MDD and SZ, and the kynurenine to tryptophan ratio is increased in MDD and SZ. Our results suggest that there is a shift in the tryptophan metabolism from serotonin to the kynurenine pathway, across these psychiatric disorders. In addition, a differential pattern exists between mood disorders and SZ, with a preferential metabolism of kynurenine to the potentially neurotoxic quinolinic acid instead of the neuroprotective kynurenic acid in mood disorders but not in SZ.
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What OpenQuestion holds
Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.